From the valley of the Pacamayo, the trail climbs steeply up the opposite side of the valley wall, towards the second pass. About halfway up is a small round roofless stone building. This Inca ruin is known as Runkurakay ("Pile of Ruins"). The building is thought to have been a tambo, a kind of way post for couriers following the trail to Machu Picchu. It contained sleeping areas for the couriers and stabling facilities for their animals.
After Runkurakay, the trail continues to climb towards the second pass, the Abra de Runkurakay, which is at around 3500m. On the far side of the pass, the trail descends towards a valley containing a shallow lake. At around this point, the trail changes from a dirt path to a narrow stone roadway. This is the beginning of the true Inca Trail; the stones of the roadway were laid by the Quechua people of the period of the Inca Empire.
The trail leads to a second, larger Inca ruin, Sayacmarca ("Town in a Steep Place"). Sayacmarca effectively controls the trail - which passes beneath it - at this point. It is built on a promontory of rock overlooking the trail, and is accessible only via a single narrow stone staircase. On the left of the staircase, which is about a metre or less in width, is an overhanging rock wall, which makes it difficult for a tall man to climb, while on the right is a sheer drop onto the rocks below.
Sayacmarca (which Bingham inexplicably decided to name Cedrobamba - "Plain of Cedars" -- despite the fact that there are no cedars to be seen, and it's perched on a spur overlooking a valley) is roofless and overgrown, but the walls still stand and the shape of the fortress can easily be seen. Nearby is a stone aqueduct which once carried water to the site.
After Sayacmarca, the trail descends to the valley floor, and the roadway takes the form of a long causeway leading across what may once have been the bed of a shallow lake. On the far side, the trail begins to climb again. The roadway represents a considerable feat of engineering, including even an 8m tunnel section where the Inca engineers widened a natural fissure in the rock into a tunnel large enough to allow the passage of men and animals.
The trail leads up to the third pass and, just beyond it, a third Inca ruin, Phuyupatamarca ("Cloud-level Town"). This site appears to have had some ritual function; the rectangular structures along one side are baths, which were apparently fed from a spring higher up. Archaeologists believe that the highest bath was reserved for the nobles, while the lower classes performed their ritual ablutions in the water which had already been used by the aristocracy.
Below Phuyupatamarca, the trail spirals and descends steeply towards Huinay Huayna, ("Forever Young"), the site of another Inca ruin. There is another campsite and a visitor centre nearby.